Piggot P J, Curtis C A, de Lencastre H
J Gen Microbiol. 1984 Aug;130(8):2123-36. doi: 10.1099/00221287-130-8-2123.
Plasmids carrying different portions of the polycistronic spoIIA locus, and unable to replicate autonomously in Bacillus subtilis, were able to transform a Spo+ B. subtilis strain, BR151, for the plasmid-determined chloramphenicol resistance by Campbell-like insertion into the region of homology on the chromosome. Two such plasmids, pPP35 and pPP36, yielded Spo- transformants, indicating that the cloned regions of these plasmids were entirely within the chromosomal spoIIA transcriptional unit. The cloned regions overlapped the end of a known spoIIA cistron, so that the transcriptional unit was larger than this cistron, and was polycistronic. This is the first demonstration of such a polycistronic sporulation transcriptional unit. The DNA sequence of the region has now been determined (given in an accompanying paper) and suggests a transcriptional unit with three open reading frames. Two other plasmids yielded Spo+ transformants of BR151, and these define the outer limits of the transcriptional unit. The adjacent sporulation locus identified by the spoV A89 mutation was not part of the same transcriptional unit.
携带多顺反子spoIIA基因座不同片段且无法在枯草芽孢杆菌中自主复制的质粒，能够通过类似坎贝尔式的插入染色体上的同源区域，将一个Spo+枯草芽孢杆菌菌株BR151转化为具有质粒决定的氯霉素抗性。两个这样的质粒pPP35和pPP36产生了Spo-转化体，表明这些质粒的克隆区域完全位于染色体spoIIA转录单元内。克隆区域与已知spoIIA顺反子的末端重叠，因此转录单元比这个顺反子大，并且是多顺反子的。这是首次证明这样一个多顺反子孢子形成转录单元。该区域的DNA序列现已确定（见随附论文），并提示有一个具有三个开放阅读框的转录单元。另外两个质粒产生了BR151的Spo+转化体，它们确定了转录单元的外部界限。由spoVA89突变鉴定的相邻孢子形成基因座不是同一转录单元的一部分。
